The long-range goal of this project is to develop methods for enhancing motor function in patients with motor disabilities. Our approach to improving motor function has been to couple assisted movement with enhanced sensation ("AMES"), in which the patented AMES device assists the patient in moving an affected limb while at the same time it vibrates the lengthening tendons to enhance the patient's sensation of the movement. In a Phase I clinical trial, AMES treatment of 22 low-functioning chronic stroke patients (14 upper and 14 lower extremities) resulted in improved strength, range of motion, and functional movement in about 70% of the patients. The current method of 'enhancing sensation'in AMES was a first approach - to vibrate the lengthening muscles at a constant 60 pulses per second. The objective of the proposed research is to intensify the patient's perception of the assisted movement by optimizing the methods of sensory stimulation. The overall hypothesis is that, by optimizing the patient's perception of movement with AMES therapy, connections between a joint's antagonistic sensory and motor connections to the brain are further strengthened, leading to improved motor function. Aim 1 will identify psychophysical methods that optimize kinesthetic amplification during movement. Two experiments will address Aim 1: Exp.1 will differentiate among the contributions of joint, muscle, and skin receptors during a kinesthetically controlled hand movement;Exp.2 will investigate whether, during precise voluntary joint movement, antagonist muscles are co-activated and whether, as a consequence, the sensitivity of antagonist muscle spindles is enhanced by fusimotor drive.